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  	Improve byte-code compilation of unboxed
	 	tuple returns
		------------------

The previous byte-code for returning unboxed tuples was just wrong.  It's
a special case for the situation where we return (# s, x #), where s is
a state token, so we can just return the single result 'x' on top of the
stack.  Previously we generated an ENTER at the end, which is plain wrong.
We should RETURN.

It still doesn't work, for other tiresome reasons...but rather than fix it
we'll wait for eval-apply.  Meanwhile it's less wrong than before.